Next-Gen Challenges of LTE RF Design

With Long Term Evolution (LTE), you've got the whole world in your hand … or a global ecosystem, anyway. It's going to be a while before you can hold an LTE tablet or smartphone that will work nearly anywhere in the world the way its GSM or UMTS ancestors can.

That's the double-edged sword of LTE: Virtually the entire cellular world is migrating to it, which means enormous economies of scale over the long term. In the short term, operators and regulators are scrounging for every bit of available spectrum for LTE. The result is more than 40 potential bands, roughly 19 of which are currently in use.

Smartphone OEMs would love to have a small set of core LTE bands that they could build into their devices so they will work in most parts of the world. As explained in the new Heavy Reading 4G/LTE Insider, "LTE RF Design: Problems & Opportunities," this desire isn't so much because there's an enormous market for LTE devices that can roam globally. Instead, it's more so that OEMs can have as few SKUs (stock keeping units) as possible for each device model and still tap the widest possible market. Minimizing SKUs will become increasingly important as operators launch LTE in developing markets, where price sensitivity makes it financially difficult to have operator- or country-specific SKUs.

LTE also has the challenge of arriving in the middle of a trend toward ever-thinner smartphones and tablets. Those form factors make it difficult to find room for antennas not only for multiple LTE bands, but also for 3G/2.5G/2G fallback, Bluetooth, NFC, Wi-Fi and GPS. "These devices can become a porcupine," says a Tier 1 U.S. operator executive.

By some estimates, the thin-is-in trend is reducing the space available for antennas and other radio frequency (RF) components by 25 percent per year. For device OEMs, the good news is that there's no shortage of vendors -- Ethertronics Inc., Qualcomm Inc. and SkyCross Inc. among them -- stepping up with antennas and other RF solutions designed to accommodate these and other LTE challenges. The trick is convincing OEMs that hardware such as active antennas are key for not only delivering regional or global LTE roaming, but also for the performance that users expect from 4G.

"They've gotten used to paying pennies for antennas," says one chipset vendor, referring to device OEMs. "To them, it's just a piece of stamped metal. These active antennas and tunable antennas, they consume power and take up more footprint and they cost more. So there's this hesitancy to go to a premium-priced component that they're used to paying pennies for."

What could change their minds? One thing is a reputation for poor performance. As it happens, this report was written just as some iPhone 4 owners were receiving US$15 checks as part of a class action settlement for "Antennagate" -- the mini scandal that erupted after initial buyers reported dropped calls and other signal-related problems based on how they held their iPhone. It's not a stretch to call Antennagate a wake-up moment for vendors and operators about how RF design directly affects everything from brand reputation to the bottom line.

LTE's RF challenges aren't limited to smartphones and tablets. Some chipset vendors predict that LTE-only RF modules (sans antennas) will drop to $20 in volume by the end of this year. That decline means OEMs of digital cameras and other CE devices, as well as commercial products such as video surveillance cameras, will increasingly want to add LTE to their products. Doing so will be easier said than done because those companies typically lack in-house RF design experience. As a result, there will be opportunities for antenna manufacturers and other RF vendors to provide those OEMs with LTE solutions that they can basically drop into their products, rather than taking on the cost and lead time of trying to develop those on their own.

RF systems are one more example of how LTE isn't a market where any vendor can parachute in and assume success. But for those that have what it takes, there's a lot of money to be made by solving all of those problems.

— Tim Kridel, Contributing Analyst, Heavy Reading 4G/LTE Insider

This report, "LTE RF Design: Problems & Opportunities," is available as part of an annual subscription (6 issues per year) to Heavy Reading 4G/LTE Insider, priced at $1,595. Individual reports are available for $900. To subscribe, please visit: www.heavyreading.com/4glte.